1. Field of the Invention
The present invention relates to an apparatus for washing an alignment film printing mask and a method for fabricating a display device using the same, and more particularly, to a jig for washing an alignment film printing mask.
2. Discussion of the Related Art
Owing to advantages of low voltage driving, full color reproduction, light/thin/short/small configuration, a low power consumption, and so on, liquid crystal display devices have become widely applied to electronic devices ranging from watches, calculators, notebook computers, to PDAs, TVs, cellular phones, monitors for air planes, monitors for PCs, and so on.
In order to use the liquid crystal display devices, it is required to orient liquid crystal molecules in a particular direction. To do so, an organic polymer film called as an alignment film is formed on an ITO electrode. The alignment film is formed by coating a liquid raw material of the alignment film, for example, polyamic acid, soluble polyimide, or the like, on a substrate, polyimidizing (or curing) the liquid raw material, and rubbing the cured polyimide. That is, the liquid raw material of the alignment film is printed on a upper surface of the substrate with an alignment film printing apparatus, and the liquid raw material of the alignment film is heated to a temperature in a range of 60° C.˜ 80° C. to primarily cure the liquid raw material, and is then heated to a temperature in a range of 80° C.˜ 200° C. to secondarily cure the liquid raw material. Thereafter, the alignment film is formed by rubbing the surface of the raw material of the alignment film or by directing a beam of light onto it.
The alignment film is generally printed on either the substrate having a TFT pattern formed thereon or the substrate having a color filter pattern formed thereon using three rolls of a doctor roll, an anilox roll and a printing roll, and an alignment film printing mask (hereinafter referred to as “mask”). The mask is generally constructed of a rubber plate (APR “Asahi Kasei Photosensitive Resin” rubber plate) having a predetermined pattern with openings. When the mask is repeatedly used, polyimide (PI) used during the formation of the alignment film gradually accumulates at the openings. Therefore, it is required to wash the mask at appropriate intervals to remove the remains of polyimide from the openings. A mask washing apparatus is separately used to do so.
The mask washing apparatus is provided with a washing tank filled with N-Methyl Pyrrolidone (NMP) liquid and a jig for holding the mask. The height of the washing tank is generally greater than the height of the mask. The mask held by the jig is introduced into the washing tank.
Recently, as the size of the liquid crystal display devices has become larger, the size of the mask has become larger. Thus, the size of the jig and the height of the washing tank are required to become larger to wash the large-size mask. Due to this trend, the consumption of NMP for washing the mask is sharply increased, which increases the fabrication cost.
In addition, because the recent mask has a height in a range of 2000˜3000 mm, a height of a clean room storing the production equipment is required to be in a range of 5000˜6000 mm to introduce the mask into the washing tank. As a result, a separate clean room space is required to install the mask washing apparatus, which further increases the fabrication cost.
Moreover, because the jig holding the mask is taken out of the washing tank after a predetermined time period in a series of washing steps, the washing process is not effective. Also, the remains of NMP on the mask impair the printing performance of the alignment film mask.